In the modern wireless communication system, usually the smart antenna is deployed in order to raise system capacity and sensitivity and to have communication for longer distance with lower transmission power.
In the China Patent CN99 1 11350.0 named “a calibration method of a smart antenna array and a device thereof”, the real-time calibration device of the smart antenna includes a calibration link that is the connection of a coupled calibration network, a feeder cable, and a beacon transceiver; wherein the coupled calibration network connects with the antenna units accordingly, and the beacon transceiver connect with a baseband processor. The calibration steps are as follows: with the Vector Network Analyzer, pre-calibrating the coupled calibration network and recording transmission-coefficients of the coupled calibration network for receiving and transmitting; making receiving calibration: the transmission-coefficient amplitude of each receiving link is adjusted to the same as the transmission-coefficient amplitude of the reference link, and the transmission-coefficient phase difference φ between each receiving link and the reference link is stored in the baseband processor; making transmitting calibration: the transmission-coefficient amplitude of each transmitting link is adjusted to the same as the transmission-coefficient amplitude of the reference link, and the transmission-coefficient phase difference Ψ between each receiving link and the reference link is stored in the baseband processor.
In the China Patent CN01 1 20547.4 named: “A couple calibration method and network of smart antenna array for a wireless communication system”, based on the last patent, the couple calibration method and device are further designed in order to solve the problems: the receiving calibration accuracy of the receiver and the transmitting calibration accuracy of the transmitter in the base station are influenced by the smart antenna installation environment and landscape; and the performance during calibration is consistent with that during production.
In the above calibration techniques, the calibration method and device of the smart antenna array must have a beacon antenna or a coupled calibration network and must have a specific calibration link. The first patent concerns about the calibration at any time, but it lacks of a specific method to calibrate the smart antenna array during it is running.